The Tropic of Capricorn is one of the five major circles of latitude that mark maps of Earth. As of 16 August 2017, its latitude is 23°26′13.2″ (or 23.437°)[1] south of the Equator, but it is very gradually moving northward, currently at the rate of 0.47 arcseconds, or 15 metres, per year.[2]

The position of the Tropic of Capricorn is not fixed, but rather it varies in a complex manner over time; see under circles of latitude for information.

In Australia, areas on the Tropic have some of the most variable rainfall in the world[3] and thus even the wetter areas cannot be generally farmed, since irrigation sources invariably dry up in drought years. In southern Africa, where rainfall is more reliable, farming is possible, though yields are low even with fertilisers.

In South America, whilst in the continental cratons soils are almost as old as in Australia and Southern Africa, the presence of the geologically young and evolving Andes means that this region is on the western side of the subtropical anticyclones and thus receives warm and humid air from the Atlantic Ocean. As a result, areas in Brazil adjacent to the Tropic are extremely important agricultural regions, producing large quantities of crops such as sugarcane, and the natural rainforest vegetation has been almost entirely cleared, except for a few remaining patches of Atlantic Forest. In and west of the Andes, however, the Humboldt Current makes conditions extremely arid, creating the Atacama Desert, one of the driest in the world, so that no glaciers exist between Volcán Sajama at 18˚30'S and Cerro Tres Cruces at 27˚S.[4]Vegetation here is almost non-existent, though on the eastern slopes of the Andes rainfall is adequate for rainfed agriculture.

As the major portion of earth's land is located in the Northern Hemisphere there are only four countries entirely south of the Tropic of Capricorn (there are 74 countries entirely north of the Tropic of Cancer):

The Tropic of Capricorn is so named because, when it was named about 2,000 years ago, the sun was also in the direction of the constellationCapricornus (capricorn is Latin for goat horn) at the December solstice. In modern times the sun appears in the constellation Sagittarius during this time. The change is due to precession of the equinoxes. The word "tropic" itself comes from the Greek trope (τροπή), meaning turn, change in direction or circumstances, referring to the fact that the sun appears to "turn back" at the solstices.